Treating oil



atented ct. 3, i933 TREATENG (in:

Matthew G. Barradas, San Leandro, Galiifi, as-

signor to The Best Foods, Inc., New York, N. Y" a corporation of New .lersey NoDrawing. Continuation of application Serial No. 419,470, January 8, 1930. This application .luly 19, 1930. Serial No. 469,289

This invention relates to the refining of oils and more particularly to the removal of the particles of soap solution remaining suspended in the oil after the oil has been neutralized.

In the refining of vegetable oils such as cocoanut oil, palm kernel oil, or mixtures of these, the usual practice is to heat the oil to about 135 F. with mild mechanical agitation and to add a quantity of 12 Baum solution of lye, suificient to neutralize the free fatty acids present in the batch, plus an excess of about .17 to .25 percent, depending upon the fatty acid content of the oil. The batch is agitated during the admission of the caustic solution and the agitation is continued thereafter for about thirty minutes, after which the mixture is allowed to settle for at least three hours.

The neutralized oil, produced by the above procedure, contains particles of soap solution in suspension. These particles are difficult to separate from the mass of oil and are objectionable in the subsequent filtering operations. The usual procedure for separating these particles is to wash the oil repeatedly with clear water. This procedure consumes time and leaves a certain amount of water in suspension in the oil, which would interfere with subsequent filtering operations and would be objectionable in the finished product. It has been necessary, therefore, to dry the oil after washing, preferably by heating it in a vacuum drier.

It has been suggested to add a carrier, such as fullers earth, impregnated with caustic in a dry state to the unrefined or semi-refined oils in place of the usual neutralization step. Such a procedure is objectionable because the carrier becomes intimately mixed with all of the soap stock resulting from the neutralization and requires an additional separation step before the latter may be used. Furthermore, the preparation of the impregnated carrier in'a dry state requires the evaporation of the solution used to impregnate the carrier and the grinding of the impregnated carrier or a trituration of the dry caustic with the carrier. Both of these operations are expensive and time consuming.

It is an object of my invention to avoid the above difliculties in the separation of soap stock from oil, and to improve the quality 'of the refined product. It is another object to provide an improved method for separating the soap stock resulting from the neutralization of free fatty acid in oils and to do so without the addition of solid materials to the oil in advance of the removal of the soap stock. A further object is to provide an improved method for separating soap stock, which method avoids the repeated Washing of the oil after the usual neutralization step to which the oil is subjected, and which avoids the subsequent drying of the oil. It is also an object to separate the soap stool; without the addition of dry chemicals or a carrier to the oils. Another object of the invention is to provide an improved method for separating the dilute soap stock solution which remains suspended in oil after neutralization by the usual wet method. Other objects will become apparent.

I have found that by adding a concentrated caustic solution to the neutralized oil, the soap and water particles will be absorbed and can be readily separated from the refined oil. The quantity of caustic solution to be added should be such that it will absorb all of the water without any substantial saponification of the oil.

In a preferred embodiment of my process a neutralized oil, for example, such as results from the procedure described above, is separated from the main portion of the soap stock which settles to the bottom of the neutralizing kettle during the period of rest following the agitation with the caustic solution. The oil-is then allowed to 0001 until it reaches a temperature of about 115 to 120 F. The batch is then mechanically agitated and a small quantity of water, for example, about .05% by weight, is added. This is followed by the admission of about 12% by weight of 50 Baum sodium hydroxide solution. The agitation is continued and after about 30 minutes an additional small quantity of 50 Baum sodium hydroxide is added, for example about .03 After the addition of the second quantity of sodium hydroxide solution the agitation is continued for about 30 minutes and the batch is then allowed to settle.

Upon the addition of the concentrated caustic solution, the soap'stock'su'spended in the oil separates out in the form of an amorphous mass. The clear oil may be easily separated from this mass, for instance by decantation'; and may be passed into a bleaching tank where it is treated with a bleaching agent, such as a decolorizing carbon, fullers earth or mixtures of these materials. After agitation with the bleaching material, the oil is passed through a dry filter press in which the decolorizing material is separated from the refined oil, and the latter may then be passed to storage.

The amorphous mass separated from the clear oil may be used in neutralizing of the next batch of raw oil by pouring the oil into the tank in which the separated mass has been left. If this procedure is followed, water or more dilute alkali solution should be added to this mass to bring the caustic to the proper strength. The oil retained by the mass will be liberated into the fresh batch of oil poured into this tank. 7

The refined oil produced by my process is a brilliant, dry product which contains no soap in suspension. The use of my improved process-avoids the necessity of applying heat and/or a vacuum to dry the purified oil and avoids the dimculties attending the filtering of a wet oil.

My process is particularly applicable to that class of oils commonly known as non-drying oils. Such oils have the common characteristics of having a low iodin number and containing a high percentage of saturated glycerides. It is not intended, however, to restrict the process to this particular class of oils. I have described the invention as applied to vegetable oils, but it may also be used in connection with other oils, for instance,

animal and fish oils, from which it is desired to remove particles of soap solution held in suspension.

A particular embodiment of my invention has been described, but it is apparent that many other modifications of it may be utilized. The temperatures and proportions referred to in describing a specific example of the invention are not intended to be considered as limiting. the invention to the particular range of temperatures or quantities recited. Neither is it intended to restrict the invention to the particular sequence of steps described in the specific example. It is well known that different-types of oils, and even oils of the same type but from different sources, require somewhat different treatment, and suitable modifications should be made to meet the requirements of the particular oil to be treated.

Although I have described a sodium hydroxide solution as the preferred solution to separate the suspended soap stock, it is not intended to restrict the invention to such a solution. Other substances, such as sodium carbonate, sodium silicate, corresponding potassium salts and bases, alkaline-earth bases, starch, pectin and gelatin, may be used as substitutes for the sodium hydroxide in this connection. Neither is the particular concentration described essential to the operation 'of the process-since a more. concentrated and a somewhat less concentrated solution may be used.

While I prefer to add the caustic in the form of a concentrated solution, it may also be added in the solid form, in which event it may be desir able to add more water to givethe proper concentration of caustic solution in the mixture.

This application is a continuation of my application Serial No. 419,470, filed January 8, 1930.

By following my improved process, the majority of the soap stock may be separated from the neutralized oils by settling after' the usual neutralizing step. The remaining dilute soap solution, which is dispersed throughout the oil, is removed by the agitation with the concentrated caustic solution and the subsequent settling and/ or filtration steps. If further decolorizing is required, this may be accomplished by the usual methods employed for that purpose.

In using the term soap stock, reference is made to the dregs or residue resulting from the neutralization of free, fatty acids in the oil.

What I claim is:

1. In the purification of non-drying oils, the steps comprising neutralizing the free fatty acid in the oil with a caustic solution, settling and drawing off the soap stock, and separating out the sustling and drawing off the soap stock, cooling the' oil and agitating it with a less than about 1% of naustic solution of a concentration of not less than about 50 Baum and in a quantity sufiicient to precipitate the suspended particles of soap without substantial saponification of the oil.

3. In the purification of oils of the class described, the steps comprising heating the oil to about 135 F. with caustic solution to neutralize the free fatty acids, settling and drawing 01f the soap stock, cooling the oil to about 115 to 120 F., agitating it with less than 1% of 50 Baum caustic alkali solution, separating the oil from the precipitate, agitating the oil with a bleaching agent and filtering the bleached oil.

4. A process for separating suspended soap stock from non-drying oils containing such suspension comprising separating the suspended soap stock by agitating the oil with less than about 1% of caustic solution of a concentration of over about 50 Baum.

5. A process for purifying a low iodin number oil having a high percentage of saturated glycerides and containing soap stock in suspension, comprising separating the suspended dilute soap stock solution from the oil by agitating it with a less than about 1% of caustic solution of a concentration of not less than about 50 Baum and in a quantity sufllcient to precipitate the suspended particles oi. soap stock without substantial saponification of the oil.

6. In the separation of suspended soap stock from non-drying vegetable oils containing such suspension, the steps comprising agitating the oil at about to F. with about 0.13% of 50 Baum caustic alkali solution and separating the 120 precipitate.

7. A process for treating non-drying oils comprising neutralizing the free fatty acid in the oil, settling and drawing ofi the soap stock and separating the particles remaining suspended in the oil by agitating with less than about 1% of not less than a saturated solution of one of the group of compoundsincluding alkali and alkaline earth, salts and bases, pectin, starch and gelatin.

8. A process for treating non-drying oils comprising neutralizing the free fatty acid in the oil by agitating with a dilute basic solution, settling the soap stock and separating the particles remaining suspended in the oil by adding less than 1% of caustic alkali.

9. A process for treating non-drying vegetable oils comprising neutralizing the free fatty acid in the oil by agitating with a dilute basic solution settling and drawing off the soap stock and separating the particles remaining suspended in the oil by adding a less than about'1% of caustic solution of a concentration of not less than about 50 Baum and in a quantity sufiicient to precipitate the suspended particles of soap stock without substantial saponification of the oil.

10. A process as defined in claim 1 in which the residue from the addition of the concentrated caustic solution is used to neutralize the next batch of oil.

11, A process for treating vegetable oils, com- 150 prising neutralizing the free, fatty acid-inthe oil by agitating with a dilute basic solution, settling and drawing oiT the main portion of the soap stock produced thereby, and separating the suspended particles remaining in the oil by tralize the free, fatty acids, separating the main portion of the soap stock produced thereby and mixing less than about 1% of a caustic soda solution more concentrated than about a 50? Baum solution with the oil to precipitate the suspended soap stock. I a

13. In the purification of oils of the class described, the steps comprising agitating and heating the oil with about a 12 Baum caustic soda solution to neutralize the free, fatty acids, separating themain portion of the soap stock produced thereby, cooling the oil and agitating suflicient caustic soda solution of not less than about 50 Baum with the oil to precipitate the suspended soap stock without substantial saponification of the oil.

14. In the separation of suspended soap stock from an oil of the type described containing such suspension, the steps comprising agitating the oil with less than 1% .of caustic alkali more concentrated than about 50 Baum solution.

15. In the separation of suspended soap stock from an oil of the type described containing such suspension, the steps comprising agitating the oil with about .12 to 1% by weight of a solution of sodium hyroxide of a concentration of not less than about 50 B. and allowing the batch to settle.

16. In the separation of suspended soap stock from an oil of the type described containing such suspension, the steps comprising agitating the oil with about .12 to 1% of a sodium hydroxide so1ution of a concentration of not less than about 50 B. and in a quantity sufiicient to precipitate the suspended particles of soap stock without substantial saponification of the oil.

17. In the separation of suspended soap stock from an oil of the type described containing such suspension, the steps comprising agitating the oil for about 30 minutes with about .05% of water and about 12% of a 50 B. sodium hydroxide solution, adding about .03% more of the 50 B. sodium hydroxide solution, further agitating for about 30 minutes and allowing the batch to settle.

MATTHEW G. BARRADAS. 

